Comparing cellular bone matrices for posterolateral spinal fusion in a rat model.

Cellular bone matrices (CBM) are allograft products that provide three components essential to new bone formation: an osteoconductive scaffold, extracellular growth factors for cell proliferation and differentiation, and viable cells with osteogenic potential. This is an emerging technology being applied to augment spinal fusion procedures as an alternative to autografts. We aim to compare the ability of six commercially-available human CBMs (Trinity ELITE®, ViviGen®, Cellentra®, Osteocel® Pro, Bio4® and Map3®) to form a stable spinal fusion using an athymic rat model of posterolateral fusion. Iliac crest bone from syngeneic rats was used as a control to approximate the human gold standard. The allografts were implanted at L4-5 according to vendor specifications in male athymic rats, with 15 rats in each group. MicroCT scans were performed at 48 hours and 6 weeks post-implantation. The rats were euthanized 6 weeks after surgery and the lumbar spines were harvested for X-ray, manual palpation and histology analysis by blinded reviewers. By manual palpation, five of 15 rats of the syngeneic bone group were fused at 6 weeks. While Trinity ELITE had eight of 15 and Cellentra 11 of 15 rats with stable fusion, only 2 of 15 of ViviGen-implanted spines were fused and zero of 15 of the Osteocel Pro, Bio4 and Map3 produced stable fusion. MicroCT analysis indicated that total bone volume increased from day 0 to week 6 for all groups except syngeneic bone group. Trinity ELITE (65%) and Cellentra (73%) had significantly greater bone volume increases over all other implants, which was consistent with the histological analysis. Trinity ELITE and Cellentra were significantly better than other implants at forming new bone and achieving spinal fusion in this rat model at week 6. These results suggest that there may be large differences in the ability of different CBMs to elicit a successful fusion in the posterolateral spine.

Informations de copyright

© 2020 The Authors. JOR Spine published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society.

Déclaration de conflit d'intérêts

This study was supported by a research grant received by B.J. and J.Y. from Orthofix Medical Inc. (Lewisville Texas) and MTF Biologics (Edison, New Jersey). J.T.R., E.I.W. and N.Z. are employees of and own stocks in Orthofix Medical Inc. E.S. and D.W. are employees of MTF Biologics. Since MTF Biologics and Orthofix Medical Inc. are the manufacturer and distributor of the Trinity ELITE allografts, the following procedures were taken to mitigate the potential conflict of interest: (a) animal surgeries were performed with rigorous randomization and blindness, including surgeries of the seven graft types being randomly placed into the surgery schedule; (b) two surgeons were randomly assigned to the surgery and not aware of the allograft name on the day of surgery; the surgeries for each allograft were split between the two surgeons; (c) careful anonymity of implant type was kept during the data collection and analysis. Manual palpation was performed by three independent reviewers with no information of graft type at the time of evaluation. MicroCT scans and histological sections were analyzed by two independent parties, who received only the coded samples with no allograft information; (d) per the research agreement between the sponsor (Orthofix) and Principal Investigator (OHSU), the Principal Investigator has the right to independently publish any research findings from this study based on their academic judgment and discretion.